1. Field of the Invention
The present invention relates to a wire grid polarizer and a backlight unit manufactured using the wire grid polarizer in which by controlling transmission rates of respective wavelengths depending on angles of incident lights, color variations can be minimized.
2. Description of the Related Art
In general, a polarizer or polarizing device refers to as an optical device for drawing linearly polarized light having a specific vibration direction among non-polarized lights such as natural light. In addition, a wire grid polarizer is a kind of optical devices for producing polarized light using a conductive wire grid. The wire grid polarizer has been used as a reflective polarizer in an infrared wavelength region since it has a high polarization separation capability, compared with other polarizers.
Generally, in a case where a cycle of metal line placement is shorter than a half-wavelength of an incident electromagnetic wave, a polarized component (s wave) parallel to the metal line is reflected and a polarized component (p wave) vertical to the metal line is transmitted. Here, a planar polarizer having an excellent polarization efficiency, a high transmission rate and a wide view angle cab be manufactured using the phenomenon as described above, which refers to as a wire grid polarizer.
FIG. 1 is a view illustrating a configuration and function of a prior wire grid polarizer wherein metal grids 2 having a predetermined thickness h are placed on a substrate 1 in a predetermined cycle A and the cycle of fine metal grid of a wire grid polarizer may be less than a half of a visible light wavelength. In case where the cycle of a metal line in the wire grid polarizer is much smaller than a wavelength of incident light, when non-polarized light is incident, a component having a vector orthogonal to a conductive wire grid, i.e., p polarized light is transmitted, and a component having a vector parallel to the wire grid, i.e., s polarized light is reflected.
In the prior wire grid polarizer, a polarization plate of a reflective-type is manufactured by forming fine metal grids directly on a substrate; however, as an incident angle becomes larger through the fine metal grid formed directly over a substrate, a transmission rate is varied depending on a wavelength of incident light and thus a color implementation depending on a view angle is limited.